Chapter 6 Chemical Bonds and Compounds

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Chapter 6Chemical Bonds and Compounds

• Come Together
• By John Lennon
• YouTube - John Lennon - Come Together (The
  Beatles Cover)

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How do these skydivers stay together? How is
this similar to the way atoms stay together?
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Objectives

• Describe how compounds are made from combinations
  of atoms.
• Explain how chemical formulas represent chemical
  compounds.

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Section 6.1

• If we look at all the different things around us
  it is easy to see that everything is not an
  element. But we also know that there are just
  over 100 different elements and they make up
  millions of different substances.
• How many letters in the alphabet?
• How many words are made from those 26 letters?
• Atoms are held together in compounds by chemical
  bonds.

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• Bonds determine the properties of a compound.
• Many times the properties of compounds are often
  different from the properties that make them.
• EXAMPLE

CALCIUM CHLORIDE
CALCIUM
CHLORINE
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• CALCIUM A GROUP 2 ALKALINE EARTH METAL (soft,
  silvery metallic solid)
• CHLORINE A HALOGEN is a greenish gas very
  poisonous to humans
• These two come together to form a product we use
  to melt ice that forms on streets and sidewalks.
• It was one of the powders in the Baggie Blast
  experiment we did a couple of weeks ago.

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In every family the number of males to females
varies. In my family there are 3 females to 2
males. Me, mom and my sister THE GIRLS. Dad and
my brother THE BOYS. So there is a 32 ratio of
females to males.
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• Atoms always combine in predictable numbers
• For example NH3 is ammonia. The compound ammonia
  always has three hydrogen atoms for every
  nitrogen atom.

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Chemical formulas

• Chemical formulas use chemical symbols to
  represent the atoms of the elements and their
  ratios.

C
O
2
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This chart shows the names, atoms, ratios and
chemical formulas for several chemical compounds.
Notice methane and propane are made from atoms
of the same elements but in different ratios. Two
totally different substances Propane in the
tank on your grill and methane given off when
cows BURP!!!!!!!!!!!!!!!!!!!
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Same elements, different compounds
Which one would you want to drink?
or
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Review

• How many different atoms are in C12H22O11?

12 carbon atoms 22 hydrogen atoms 11 oxygen
atoms 45 total atoms

• How do properties of compounds compare with the
  elements that make them?

• Most of the time VERY different

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• If a chemical formula has no subscripts, for
  example CO (carbon monoxide)
• What is the ratio of the atoms?

1 to 1
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• If CO2 is carbon dioxide then is H2O Dihydrogen
  monoxide? No silly teacher H2O is water!!!!!!!!!

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Section 2objectives

• Explain how electrons are involved in chemical
  bonding.
• Describe what the different types of chemical
  bonds are.
• Determine how chemical bonds affect structure.

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• What are some different ways workers connect
  materials?

Hearst Bld NYC Look for it in a new movie
Glue Nails screws
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Chemical bonds between atoms involve electrons

• Chemical bonds are the glue that holds
• atoms of elements together
• Chemical bonds have an effect on the chemical and
  physical properties of compounds

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Transfer Please!!!!!!!!

• When a college student needs money to cover rent
  and other needs they call mom and dad and ask
  them to transfer money to their checking account.
  Mom or dad calls the bank and says they want to
  transfer money to little Johnnys account.

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A similar thing happens when the atom of a metal
transfers an electron to the atom of a
nonmetal.
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Ionic bond the force of attraction between
positive and negative ions

• Example an atom from Group 1, like sodium (Na)
  forms a positive ion Na meets an atom from
  Group 17 (a Halogen)
• chlorine (Cl) forms a negative ion Cl- the
  bond forms is ionic. NaCl is table salt.
• Just like opposite ends of a magnet attract
  these oppositely charged ions attract each other.
  

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So how we name these monsters?

• Name the positive metal element example sodium
  (Na)
• Next take the name of the negative, nonmetal
  element, chlorine (Cl) and give it the ending
  ide chloride
• Now combine the two names making that monsters
  name sodium chloride. We just call it salt!!!!

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Lets try some more!

• What would lithium and iodine be called?
• What about sodium and fluorine?
• And calcium and chlorine?
• Wow that is amazing YOU just learned to name
  ionic compounds!!!!!!!!!!!

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Salts are formed from the positive ion of a metal
and negative ion of a nonmetal.

• Not all salts are the kind we put on our French
  fries. That is NaCl.
• Calcium chloride CaCl2 is put on roads and
  sidewalks to melt snow and ice.
• The metal ion in salts give off a characteristic
  flame color as you saw in the lady liberty
  fireworks site.
• http//www.driveaway.com/lady_liberty/liberty_dl.h
  tm

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When 2 girls share the responsibilities of being
head cheerleader what do we call them?

• They are co-head cheerleaders.
• When atoms share electrons in bonding we call
  this covalent bonding.
• The electrons spend as much time around one atom
  as they do the other atom. They zip back and
  forth between atoms.
• Some common substances held together by covalent
  bonds are carbon dioxide (CO2), methane (CH4)
  and several elements exist covalently bonded to
  themselves. H2, N2, O2, F2, Cl2, Br2, I2.

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Polar covalent bonds

• A covalent bond in which the bonds are shared
  unequally.
• Water is a perfect of example of a polar covalent
  bond. That is why water is a good solvent and we
  take a bath in it!! It has both positive and
  negative parts.

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Review section 2

• What part of an atom is involved in bonding?

The electron cloud (i.e. valence electrons)

• Compare ionic and covalent bonds.

See posters
A polar covalent bond forms when?
Two atoms share electrons unequally
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Section 3 Substances properties depend on their
bonds

• Metals have unique bonds. They slide easily past
  each other giving metals their useful qualities
  (ie malleable, ductile, shiny and good
  conductors)
• Ionic and covalent bonds give compounds certain
  properties (comparison demo of salt and PDC)

Ductile??
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Bonds can make elements look different.
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Review
What are the three forms of carbon?
Diamond, graphite, and fullerene
Metallic bonds make many metals good what?
Good conductors of electricity